1. Field of the Invention
The present invention generally relates to optical recording and/or reproducing apparatuses such as those used in computers, CD players and DVD players, and particularly to a vibration damping means for an optical recording and/or reproducing apparatus which dampens vibrations among components thereof.
2. Description of Prior Art
Optical disks are in widespread use as recording media for storage of information such as images, sound, text data, etc. An apparatus which records and/or reproduces information onto or from such optical disks usually has a main body with a chassis. A spindle motor and an optical pickup unit are mounted on the chassis. When the spindle motor rotates the optical disk, the optical pickup unit emits a laser beam vertically illuminating a desired recording track formed on the optical disk. The recording tracks on the optical disk are arranged highly compactly. If the optical pickup unit is disturbed from its original precise position relative to the optical disk, the laser beam cannot follow and illuminate the correct recording track, and the apparatus cannot successfully record or reproduce information.
With the rapid improvement in recording and/or reproducing speeds, vibration is becoming an increasingly serious problem. When the spindle motor rotates at high speed, vibrations are frequently generated because of imbalance of the optical disk. These vibrations are transmitted to the optical pickup unit by the chassis, and cause the optical pickup unit to deviate from position. Vibration may also originate from the external environment. For example, the apparatus may be bumped or accidentally fall to the ground. The vibrations are transmitted to the optical pickup unit via other components of the apparatus. Furthermore, the intensity of these vibrations is generally large, and the optical pickup unit is often seriously damaged.
Conventionally, there are two kinds of means used to prevent vibration from affecting the optical pickup head. In the first means, a heavy chassis is used for supporting of the spindle motor. One major drawback of this means is that it makes the apparatus weighty and costly. Another major drawback is that it cannot effectively protect the optical pickup head from vibration originating from the external environment. In the second means, a vibration damping member is installed between the chassis and a frame which supports the chassis. The vibration damping member is usually a rubber gasket. However, this means also has drawbacks. Normally, the capacity of the vibration damping member to absorb vibration is determined by its damp coefficient. In the case where the vibration damping member has a small damp coefficient, it substantially absorbs only vibrations with small intensity and high frequency, such as vibrations produced when the spindle motor rotates. In the case where the vibration damping member has a large damp coefficient, it substantially absorbs a limited scope of vibrations with large intensity such as those produced by external impact. However, because the damp coefficient of the vibration damping member is constant, it is difficult to achieve a damp coefficient which enables the vibration damping member to satisfactorily absorb the diverse vibrations that the apparatus is generally subjected to.